11.9 Small Islands

Assessment of projected climate change for Small Islands regions:

Sea levels are likely to continue to rise on average during the century around the small islands of the Caribbean Sea, Indian Ocean and Northern and Southern Pacific Oceans. Models indicate that the rise will not be geographically uniform but large deviations among models make regional estimates across the Caribbean, Indian and Pacific Oceans uncertain.

All Caribbean, Indian Ocean and North and South Pacific islands are very likely to warm during this century. The warming is likely to be somewhat smaller than the global annual mean warming in all seasons.

Summer rainfall in the Caribbean is likely to decrease in the vicinity of the Greater Antilles but changes elsewhere and in winter are uncertain. Annual rainfall is likely to increase in the northern Indian Ocean with increases likely in the vicinity of the Seychelles in DJF, and in the vicinity of the Maldives in JJA while decreases are likely in the vicinity of Mauritius in JJA. Annual rainfall is likely to increase in the equatorial Pacific, while most models project decreases just east of French Polynesia in DJF.

Since AOGCMs do not have sufficiently fine resolution to see the islands, the projections are given over ocean surfaces rather than over land and very little work has been done in downscaling these projections to individual islands. Assessments are also difficult because some climatic processes are still not well understood, such as the midsummer drought in the Caribbean and the ocean-atmosphere interaction in the Indian Ocean. Furthermore, there is insufficient information on future SST changes to determine the regional distribution of cyclone changes. Large deviations among models make the regional distribution of sea level rise uncertain and the number of models addressing storm surges is very limited.